Piston packing



Sept. 10, 1929. CHRISTENSEN 1,727,366

PISTON PACKING Filed Aug. 20, 1926 34 4 4 a2 3a 2a i, l 7 36 I g INVENTOR.

M w W A TTORNEYS Patented Sept. 10, 1929.

1 UNITED STATES NIELS A. CHRISTENSEN, OF CLEVELAND, OHIO.

PISTON PACKING.

Application filed August 20, 1926. Serial No. 130,438.

The invention relates to piston packing. The object of the invention is to provide a piston packing of simple and eflicient construct-ion in which a thin metal packing disk is clamped at it central portion to the piston, and whose scaling flange engaging the bore is normally held against said bore by the inherent flexibility of a spring ring alone.

The invention further consists in the several features hereinafter set forth and more particularly defined by claims at the conclusion hereof.

In the drawings Fig. 1 is a vertical sectional View of a brake cylinder having its piston equipped with the packing construction embodying the invention;

Fig. 2 is a vertical sectional view through a compressor or motor piston equipped with the packing construction embodying the invention.

Referring to Fig. 1. the numeral 4 designates the main body of a brake cylinder having a bore 5 and closed at its ends by covers 6 detachably secured thereto by bolts 7 As shown, a pair of pistons work in said bore 5 and move outwardly in opposite d1- rections under the action of pressure fluid introduced into said cylinder between the pistons by Way of a port 8 connected with a suitable source of supply.

' Each piston includes a piston rod 9 slldably mounted in a guide bushing 10 in one of the covers 6 and having a reduced threaded end 11, a shoulder 12 and'an exterior head 13. A piston head 14 in the form of p a metal disk fits over thereduced end 11 and abuts against the shoulder 12.

The piston packing construction includes a thin metal cup 15 having an annular flange 4 portion 16 engaging the bore 5 and a flat disk portion 17 abutting against the head 14 and fitting over the end 11 of the rod 9. The cup adjacent its central opening 18 is firmly clamped to the head by an annular plate 19 whose central opening has threaded engagement with the threaded end 11 of the rod 9. This plate 19 only engages the cup 15 at its central portion so that the greater part of its disk area is free but the cup being tightly clamped between the plate 19 and the head 14 serves as a gasket to prevent the escape of pressure fluid along the rod 11 past the head 14. The plate 19 in addition to acting as a clamp for the cup 15 also acts as a filler to reduce the clearance 5 space in the pressure chamber so that the piston will respond quickly to differences in' pressure existing in the pressure chamber, which in the form shown is between the pistons.

In order to normally hold the flange portion 16 of the cup in engagement with the. bore 5 a spring ring 20, having the usual split joint, is adapted to fit within the sides or annular wall of the cup and by its in- 5 herent elasticity act against said flange portion. This ring, while generally similar to the usual piston rings, does not as shown in the drawings, engage the flange 16 throughout its width but is preferably bev-, elled at its edges and relieved along an an-' nular area at 22 so that it presses more particularly upon the outer edge portion of the sides of the cup or flange portion 16. The

. plate 19 has an annular projection 23 which extends over the front edge of the ring 20 but with a clearance space 24 therebetween to allow free action of the spring 20. A working clearance defined -by the annular space 25 is provided between the plate 19 and the inner side of the ring.

When two pistons are used the followers or plates 19 abut each other when the pistons are in release position but owing to the fact that the annular portions-23 of these plates are spaced from the walls of the bore 5 and a groove or grooves 26 are provided in the faces ,of the plates 19, the air is free to enter or exhaust from the space between the plates.

With this construction, when the pressure fluid,' such as compressed air, is introduced into the space between the piston it passes through the clearance spaces 24 and 25 and the clearance space 27, putting pressure upon the front face of the cup and expanding its sides against the bore 5, thereby providing a seal against the escape of air as the pistons are moved outwardly under this pressure. Upon the release of the pressure fluid 100 In the construction shown in Fi 2 the numeral 27 designates the main bo y of a compressor or motor piston which has apiston ring 28 adjacent the piston pin. opening 29 for holding .the piston pin,'not shown, against longitudinal movement against the walls of the cylinder in which the piston works, should-said .pin become loose.

The body 27 of the piston has a threaded projection 29 extending outwardly from its head 30 An annular follower piece or plate 31 fits over the projection 29 and a pair of oppositely disposed thin metal 'cups 32 and 33, together with a plate 34 interposed between the fiat disk portions of the cups are securely clamped together by a nut 35 em gaging the threaded end of said projection 29 and seated in an annular recess 36 within the plate 31 and provided with spanner wrench engaging openings '37. A spring ring 38, similar to the ring 20, fits within the cup 32 and exerts pressure against the sides thereof. and a similar spring ring 39 fits within the cup 33 and exerts pressure against the sides thereof so that flanged portions of the cups, for a portion of their width, are held in engagement with the sides of the cylinder-in which the piston works. The action of the cup 32 is similar to that tom abutting against the head, a member v securing the bottom portion of said cup in sealed contact with said head, and a split spring ring mounted within the sides of the cup and bevelled to normally act upon 9. limited area of the sides of the cup to press the cup against the bore of the cylinder solely by its inherent elasticity, said cup being expanded into sealing contact with the cyllnder by pressure action upon the front of the piston.

In testimony whereof I afiix my signature. NIELS A, CHRISTENSEN.

of the first described'construction when pres sure is built up in the cylinder above the top of the piston and where the same is used for a compressor the cup 33 acts during the suction stroke to 'prevent oil from passing by the piston during said stroke, which'might occur were the cup 32 used alone, owing to the tendency of the cup 32 to contract on account of the partial vacuum created during the intake stroke and thus oil pass by the piston.

To keep'the plate the bore of the cylinder and to act as a further seal, I provide a piston ring 40 seated in an annular groove 41 in said plate and in that event openings 42 are provided in said plate connecting a space 43, communicating only engages the cup 32 at its central portion and the head of the piston only engages the cup 33 at its central portion, and that these "cups, clamped as they are between the 31. out of contact with 

